14 PIN CENTRONICS FEMALE at the Computer.
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | /STB | OUT | Strobe |
| 2 | PDB0 | OUT | Data 0 |
| 3 | PDB1 | OUT | Data 1 |
| 4 | PDB2 | OUT | Data 2 |
| 5 | PDB3 | OUT | Data 3 |
| 6 | PDB4 | OUT | Data 4 |
| 7 | PDB5 | OUT | Data 5 |
| 8 | PDB6 | OUT | Data 6 |
| 9 | PDB7 | OUT | Data 7 |
| 10 | n/c | - | |
| 11 | BUSY | IN | Printer is busy |
| 12 | n/c | - | |
| 13 | n/c | - | |
| 14 | GND | - | Signal Ground |
The MSX printer port is a 14-pin Amphenol connector (female on the machine) used across all MSX-1 and MSX-2 computers from 1983 onwards. It carries 8-bit parallel data at TTL levels and uses a two-signal handshake — STROBE* and BUSY — functionally compatible with the Centronics parallel printer standard of the early 1970s, though the physical connector differs from the full 36-pin Centronics socket. Character data sent to the port uses MSX display codes. The port specification remained unchanged between MSX1 and MSX2, and I/O ports 90H and 91H are standard across all MSX machines.
Signals
- /STB — Active-low strobe output; the host asserts this line low to signal that valid data is present on PDB0–PDB7. The printer latches the data on the rising edge.
- PDB0–PDB7 — Eight-bit parallel data output (pins 2–9); carry the character byte to be printed, encoded as MSX display codes.
- BUSY — Input from the printer indicating it cannot accept new data; the host must wait until BUSY is low (0 = ready) before asserting the next STROBE*.
- GND — Signal ground reference (pin 14); pins 10, 12, and 13 are not connected.
Notes
- Direction is Computer relative Printer.
- Pin 5 carries +5 V (not listed in the table above); it is used as a power reference for the Amphenol connector but is not a data signal.
- The host writes print data to I/O port 91H; writing bit 0 of port 90H controls the STROBE* line; reading bit 1 of port 90H returns the BUSY state.
- BIOS entry points: LPTOUT (00A5H) sends one character to the printer; LPTSTT (00A8H) checks printer status; OUTDLP (014DH) sends a character with conversion.
- All signals are TTL level; the interface is not electrically identical to the full Centronics specification despite functional compatibility.
References
- MSX Technical Data Book — ASCII Corporation / Sony, 1984
- MSX2 Technical Handbook — Chapter 5a: Access to Peripherals through BIOS — ASCII Corporation / Konamiman GitHub edition